Polymerization catalyst



United States Patent 3,050,472 POLYMERIZATION CATALYST Jacque C. Morrell, 8 Oxford St., Chevy Chase, Md. No Drawing. Filed Mar. 17, 1959, Ser. No. 799,857 8 Claims. (Cl. 252435) This invention relates to polymerization catalysts and more particularly to improvements in those types of polymerization catalysts which contain as their principal ingredients a phosphoric acid and a natural porous silica material. The latter material is generally referred to as kieselguhr or infusorial earth and sometimes also as diatomaceous earth. In its most specific aspect my invention relates to improvements of the compression strength and hardness, and in general the wearing qualities of such polymerization catalysts which is at present a most important problem.

The catalysts produced from such mixtures of phosphoric acid and porous silica material, after baking and/ or drying the same, have proven to be the best available catalysts for the polymerization of normally gaseous olefins to produce liquid hydrocarbon components of high octane motor and aviation fuels. The polymerization process has for a great many years been one of the most useful and important in the economy of petroleum refining for the conversion of otherwise practically waste gases resulting from both thermal and catalytic cracking into valuable components of motor fuels. The catalyst itself is highly active for the purpose, but its outstanding weakness has been its poor wearing qualities and its tendency to crumble and to dust during handling and use. This results in a relatively short life and frequent turnover of catalyst with the attendant increased costs. Despite the many years that this problem has existed and the many attempts to solve it, no satisfactory solution has been available to the industry and it is a prime object of the present invention to relieve the refining industry of the problem.

The polymerization catalysts described in my Patents Nos. 2,586,582 and 2,713,560 consisting of kaolin and phosphoric acid were an improvement so far as wearing qualities Were concerned but the sacrifice in activity was too great to be economically feasible. However, one solution of the problem is disclosed in copending applications which are continuations-in-part of the applications upon which these patents issued. The catalyst products of these applications consist in a very minor amount of kaolin combined with a major amount of a natural porous silica material such as kieselguhr and these in turn are combined with a much larger proportion of a phosphoric acid e.g. the latter may comprise from 75% to 85% and preferably in excess of 80% of the mixture. The final product is dried and baked. Thus a balance between wearing qualities and activity is achieved. Additional different solutions of the problem are shown in other copending applications.

In my present application I have made further improvements wherein I employ a catalyst composition comprising the additive mineral talc (sometimes referred to as soapstone) and occurring in a massive form known as steatite and other similar but non-equivalent minerals particularly sepiolite as well as others of similar proper- 3,050,472 Patented Aug. 21, 1962 ties but different composition especially pyrophyllite; the said additive minerals being added or present in relatively minor proportions, in combination with a natural porous silica material of the class consisting of kieselguhr, infusorial earth and diatomaceous earth and incorporating the latter mixture with the maximum amount of a phosphoric acid, up to 80% and above; to achieve the desired balance of catalyst hardness and compression strength on the one hand and the polymerizing activity of the phosphoric acid on the other hand at relatively low cost. Each of these additives including those employed in my prior applications and the additive minerals of the present application, namely, talc (steatite), sepiolite and pyrophyllite exerts its own individual characteristics both in the preparation of the catalyst and in its final proper ties and they are thus on a non-equivalent basis. Moreover, I have discovered that the manner in which these individual materials are incorporated with the other mate rials or components as well as the materials themselves affect the quality of the final product. This further emphasizes the non-equivalency of the several additive materials employed by me.

In carrying out the objects of my invention I incorpo rate from about 3% to 5% (and in general more than 1% of the material added) at the low end of the range to from 10 to 15% (and not to exceed 20%) at the high end (based on the mineral mix) and preferably from about 5% to 10% of a mineral selected from the group consisting of talc, (steatite), sepiolite and pyrophyllite with about 85% to 97% of kieselguhr, also referred to as infusorial earth or diatomaceous earth. The preferred composition of the final product which for example contains 20% of the mineral mixture referred to above and 80% of a phosphoric acid may contain from about 1% to 2% only of the additive based on the total mixture or 5% to 10% of the additive based on the mineral mix, i.e. the kieselguhr plus the talc. Since as little as 12% on the mineral mix may show beneficial results, in some cases the content on the final product may be even lower, e.g. about /2 At the other extreme of about l5%20% (on the mineral mix) and up to about 30-40% of the latter on the total mixture, the additive would not exceed 10% on the final product even in unusual cases and on the preferred mixture would be very considerably less. The mineral mix, i.e. the kieselguhr and additive (when mixed directly) are then admixed with from about to 85% (or more generally from to of a phosphoric acid (calculated upon a basis of 100% phosphoric acid in the final mixture) and preferably in the range of 78% to 82% of the latter. In such cases the additive should preferably be present to the extent of about 5 to 10% based on the mineral mix, or 1 to 2% based on the total. This mixture may then be extruded and cut to proper size after which it is dried or baked by heating preferably in stages to from 500 F. to 700 F. (and somewhat higher for the catalyst mixture with high acid contents) for about 4 hours or longer; generally 600 F. to 700 F. for phosphoric acid contents of less than 80% and 700 F. to 800 F. and higher for phosphoric acid content above 80%.

Alternatively the dried product may be broken to size after drying, although the former procedure of extrusion is preferred.

With regard to the mineral additivestalc (and steatrte which is another type of talc in massive form) and sepiolite are all broadly naturally occurring silicates of magnesium. More specifically, they are all acid magnesium silicates and talc (and steatite) are specifically acid magnesium metasilicates (H Mg (SiO i.e. they are naturally occurring salts of silicic acid (H SiO Pyrophyllite is related chemically to tale in that it is an acid meta.- silicate of aluminum (HAl(SiO It is closely related to talc in appearance in physical properties and uses. (It may be distinguished from talc by heating with cobalt nitrate solution which turns it a deep blue whereas talc turns pink.) Tale is not decomposed by acids; pyrophyllite is partially decomposed by acids while sepiolite gelatinizes when treated with acid particularly on heating. All of these additive minerals are different in composition and properties from kaolinite and kieselguhr.

Of the additive minerals referred to above, talc is preferred because it is Widely mined and produced throughout the United States (and elsewhere) particularly in California, New York State and North Carolinia and in many other states. It has a very large number of uses in the manufacture of roofing, rubber, ceramics, paper coatings, cosmetic and medicinal preparations and others. Therefore, it may be readily and cheaply procured. Its formula is given variously as H Mg (SiO and the first one reflecting its acid magnesium metasilicate character. It has definite optical properties; a hardness of l (but varies in some cases); a gray white to pale green color with pearly luster; a specific gravity of $2.7. It usually carries about 5% of water with small quantities of iron and aluminum. It is not generally decomposed by acids (but may react at high temperatures); and on ignition loses Water and splits off silica and is converted to magnesium silicate (MgSiO It is a secondary mineral occurring as an alteration product of various silicates such as Enstatite, serpentine and actinolite.

Steatite is a massive or rock-like form of talc or soapstone and in general has the same formula and properties but may vary, e.g. from 3MgO-4SiO -H O to Its specific gravity may vary from 2.6 to 2.8 and hardness from 12.

It may also have some uses besides those for which talc is employed. Since the latter is sometimes considered as a type of talc or vice versa, the term talc will be used to cover both in the specification and claims hereof.

Sepiolite is an acid magnesium silicate and has the formula H MgSi O with about -12% H O. Its formula is sometimes given as 2MgO-3SiO -H O. It occurs in compact earthy masses and occasionally fibrous seams. It has a hardness of 2 to 2.5; a specific gravity of 12.0 and like talc, has definite optical properties. Its color is white or yellowish or grayish white. It floats on water when dry. It is associated with serpentine and in some forms is used as meerschaum for tobacco pipes. One of its unique properties is that it gelatinizes with acids which makes it adaptable to being added directly to the phosphoric acid before mixing with kieselguhr which has advantages in the process. Talc may also be incorporated directly with the phosphoric acid although it does not react as does sepiolite.

I may also employ in my process, on a strictly nonequivalent basis, natural or synthetic magnesium silicates. An example of the former is Enstatite (MgSiO The latter is quite hard (56) and of the two latter materials, the synthetic magnesium silicate is preferred.

Pyrophyllite is a natural alumino-silicate which is related to talc in that it is a meta-silicate and an acid salt of silicic acid, specifically an acid aluminum meta-silicate having the formula HAl(SiO It is sometimes referred to by the empirical formulas Al (Si.,O (OH) or A1 0 4SiO H O Its specific gravity is 2.7 to 2.9; hardness 1.5 (but may vary) and crystal structure the same as talc. Although it is sometimes considered as a clay type, its physical properties and chemical relationship are so close to those of tale that they are marketed and used for the same general purposes and grouped together for this purpose in mineral statistics generally. It is partially decomposed by acids (unlike talc) and may definitely be distinguished from talc by the cobalt nitrate test referred to above.

Is I have pointed out previously, all of these additive materials, in powdered form, may be mixed directly with the phosphoric acid, and have definite advantages, especially where they react either by being partially decomposed or gelatinizing by the acid. Even in the case of talc which is not reactive under the conditions of mixing with the acid, a smooth dispersion of the finely powdered talc in the phosphoric acid is obtained and this procedure oifers advantages; although the alternatives of mixing the talc direct with the kieselguhr or working in the talc with the mixture of kieselguhr and acid may in many cases be found desirable.

It is obvious from the above discussion that there is not only a real diiference in composition of my present catalysts product from that of the patent (referred to above), and of my copending applications, but there is at the same time a wholly unexpected and very great improvement in the hardness and compression strength of the present catalyst over that containing essentially only the kieselguhr and phosphoric acid While at the same time retaining the high activity of the latter composition.

The porous silica (SiO material, kieselguhr (as Well as infusorial earth and diatomaceous earth), are also quite diiferent from kaolin both in chemical and physical characteristics and properties. They lack plasticity and the property of hardening which kaolin possesses. The latter (sometimes called china clay) is composed of silicon, oxygen and hydrogen corresponding to the general formula Al O -2SiO -2H O. It is derived from the weathering of feldspars. Kieselguhr (etc.) on the other hand, is made up of the skeletal remains of diatoms and is essentially SiO The two materials also 'dilfer in crystal structure and X-ray pattern. In fact, there are no similarities between kaolin and kieselguhr so that a composition containing one of them is entirely different from the other.

The terms kieselguhr,-infusorial earth and diatomaceous earth (also tripolite) are used interchangeably for example, in Hackhs Chemical Dictionary (1929), and all three terms are defined as a light earthy sedimentary rock consisting of the microscopic empty shells of diatoms. I11- fusorial earth, kieselguhr, diatomite, tripolite, diatomaceous earth-siliceous earth are similarly used interchangeably and are referred to as a fine powder composed of siliceous skeletons of diatoms sp. gr. 0.24-0.34 in Chemical and Technical Dictionary (1947) and similarly in Chemical and Engineering Dictionary (both by Chemical Publishing 00.). The terms are likewise used interchangeably in Websters New Collegiate Dictionary (1951) (based on Websters New International Dictionary); Winstons Simplified Dictionary, College Edition, 1938; and Practical Standard Dictionary, Funk and Wagnalls (1929), also the Merck Index 1952 Edition and others. These materials are likewise sold and used interchangeably under these several terms; the major portion of all of them being up to as high as Si0 in the form of porous siliceous skeletal substances. Large deposits of these materials occur in various locations, e.g. California, Nevada, Oregon, etc. As with all naturally occuring materials, the Si content and impurities show variations within the general class as well as within the individual deposits. The term kieselguhr, infusorial earth and diatomaceous earth and in general such naturally occurring porous siliceous materials will be used and referred to interchangeably and on an equivalent basis in connection with the present invention. Tests on various such products showed comparable results within the variations which might be expected, i.e. the presence of other substances in varying amounts besides the porous siliceous materials in the several types. These with the higher amounts of porous silica are preferred.

The various well known phosphoric acids (ortho, pyro and meta) as well as those less well known phosphoric acids (such as tetra-phosphoric) all come within the scope of my invention. These phosphoric acids are related to each other in that they may be formed by successive dehydration steps and conversely they may be made from phosphorous pentoxide by successive additions of the proper amounts of water to P 0 Also the latter may be added to various concentrations of phosphoric acid, e.g. from 75% to 85% and higher and the resultant mixture may be assumed (as has been done in the prior art to contain phosphorous pentoxide) that is to say that the latter has been added to the former. Alternatively the mixture may contain a definite percentage of pyrophosphoric acid corresponding to the primary phase of dehydration of the orthophosphoric acid or corresponding to the primary and secondary phases of hydration of the pentoxide. Meta phosphoric acid is also formed by the dehydration of ortho and pyrophosphoric acids or by the hydration of phosphorous pentoxide. Pyrosphosphoric acid itself may be used at a temperature above its melting point of 140 F. but this is less desirable than the mixture. Therefore from the overall practical viewpoint and for convenience I prefer to use the orthophosphoric acid starting for example with the 85% commercial concentration (or diluting the latter as found desirable, e.g. from 75 to 85 to which has been added various proportions of P 0 (generally to a thick syrupy consistency); as found suitable or necessary simultaneously to incorporate the necessary amount of phosphoric acid in the mixture and to obtain a material of proper consistency prior to forming and baking. It is desirable for maximum activity to incorporate the maximum amounts possible of phosphoric acid which will produce a mixture which can be readily extruded and heated without flowing or undue deformation of the mixture during heating. Phosphorous pentoxide dissolves readily in orthophosphoric acid of commercial grade generally about 85 concentration particularly at elevated temperatures so that it is principally a question of adjustment to obtain the desired concentration of the acid in the catalyst, e.g. about 80% or more by varying the concentration and amount of these two components, but of course, the other components must also be adjusted.

In order to ascertain readily the amounts of phosphoric acid present in the mixture especially for comparison, I determine the percentages on the basis of 100% orthophosphoric acid irrespective of the concentration present during mixing and of the form in which it may be present in the final product after heating.

The heavy stiff paste or mixture made by mixing the various materials generally in powdered form including the additives, i.e. the minerals talc (steatite), sepiolite and pyrophyllite (with talc preferred) referred to above; the porous silica material, i.e. the kieselguhr and the phosphoric acid may be formed into pellets or preferably by extrusion into suitable shapes and cut into proper sizes generally /s to A diameter and about A length or otherwise formed, or the dried and baked material may be sized later.

The consistency of the mixture before drying may vary somewhat depending on the temperature of mixing, the relative proportions of the components including the specific additive, the kieselguhr and the relative amount and concentration of phosphoric acid. It is desirable in all cases that the proportions of the materials be adjusted so that the mixture is stiff enough to be formed by extrusion and dried or baked without flowing or too much deformation. The application of a relatively small amount of heat at low temperatures, e.g. about 150 F. to 200 F. after mixing assists in congealing and thickening the mixture if necessary to permit forming although this may generally be avoided by proper formulation of all the components; and even by adjustment of any one of the components after mixing, by adding one or the other as required.

The formed catalyst may be dried and/ or baked at temperatures varying from about 500 F. to about 650 F. and higher for several hours and upwards, for example 4 hours, except where the phosphoric acid content is above about 78%, e.g. from 79 to 81% in which case I may heat to temperatures from 650 F. to 800 F. and above. Preferably the heating is done in two stages, i.e. to about 200 F. to 250 F. for one half to three quarters hour and then to 600 F. to 650 F. for about three and one half to four hours. The same time schedule may be used for the higher temperatures. For some special cases, for example with very high acid contents of from to 85 I may employ temperatures progressively higher, for example from 750 F. to 800 F. or from 800 F. to 900 F (or higher as required) depending on the acid content but generally the ranges shown above suffice. However, there is a definite correlation of the composition of my catalysts with temperatures and time of heating. The prior art polymerization catalysts generally require prolonged hcating at temperatures up to and above 900 F. In some cases controlled rehydration of the baked catalysts, especially at the very high temperatures is required.

My invention thus produces a greatly superior product, more economically. It corrects vital deficiencies in respect of wearing qualities such as hardness and compression strength in the prior art catalysts while at the same time retaining the higher activity of the latter.

When used for polymerizing normally gaseous olefins, the granules or particles of catalyst are generally placed in treating towers and the gases containing olefins are passed downwardly through the towers at temperatures of 400 to 500 F. and pressures of several hundred pounds, e.g. to 350 lbs. per square inch when employing stabilizer refiuxes which contain e.g. 10 to 35% of propene and butenes. With gas mixtures containing normal and isobutene to obtain mixed polymerization the temperature may be lower, e.g. 250 to 350 F. with pressure of 500 to 800 lbs. per square inch, other reactions may be similarly carried out. It may also be desirable to introduce some steam during the reaction to maintain the normal vapor pressure of the catalyst; or the gas may be saturated with water vapor.

T 0 remove carbonaceous or hydrocarbonaceous materials which form and deposit during the treatment the catalysts are reactivated by superheated steam and/or air or oxygen at temperatures varying from 500 to 1000 F. dependent on the concentrations of oxygen. The steam concentration may be increased toward the end of the burning ofi period and then both steam and temperatures may be decreased towards the very end.

The specific examples shown in the tables following are typical of the proportions of materials used and the properties of the resulting products although they should not be construed as limiting either as to specific materials or proportions within the broad scope and spirit of my invention.

TABLE I Talc Additive Pts. by weight of 1I3PO4 72. 72.0 72.0 75. 0 78. Pts. by weight of P20 40. 0 40. 0 40. 0 42. 0 44. 0 Equiv. 0f100% H3PO- 116. 6 116. 6 116. 6 122. 0 127. 7 Percent of 100% H 1 0 78. 0 79. 0 79. 5 80.0 80. 5 Pts. by weight of kieselguhn... 30. O 29. 0 29.0 29.0 29. 0 Percent by weight of kieselguhr. 20.2 19.8 19.8 19.0 18. 3 Pts. by weight of additive. 3. 0 2.0 1. 2 1. 5 1. 5 Percent of additive 2.0 1. 4 0.7 1.0 1.0

Total, percent 100. 2 100. 2 100. 0 100. 0 99. 8

Relative hardness 2. 0 2. 0 1. 5 2. 5 2. 5 Relative compression strength 160 200 140 225 225 1 No. 5 was repeated employing 3.0 parts of additive with further improvement. Note.Prcliminary heating of all products to 250 F. for about 1 hour; No. 1 was subsequently heated to from 600F, to 650 F. for about 4 hours; No. 2 was heated in the range of 650 F. to 750 F. for about 4 hours; and Nos. 3, 4, and 5 were heated in the range of 750 F. to 850 F. for about 4 hours.

TABLE II Pyrophyllite Additive Pts. by weight of B 1 0 72.0 72.0 75.0 78. 5 Pts. by weight of P 0 40.0 40. O 42.0 44.0 Equiv. of 100 percent HaPO 116.0 116.6 122.0 127. 7 Percent of 100 percent H PO. 78. 0 79. 0 80.0 80. 5 Pts. by weight of kieselguhr 30.0 29.0 29.0 29.0 Percent by weight of kieselg'uhr 20. 2 19. 8 19.0 18.3 Pts. by weight of additive 3.0 2.0 1. 5 1. 5 Percent of additive 2.0 1. 4 1. 0 1. 0

Total, percent.- 100.2 100.2 100.0 99. 8 Relative hardness 2.0 2.0 2. 5 2. 5 Relative compression strength.... 175 210 230 220 sequently heated to from 600 F. to 650 F. for about 4 hours; No. 2 was heated in the range of 650 F. to 750 F. for about 4 hours; and Nos. 3 and 4 were heated in the range of 750 F to 850 F. for about 4 hours.

Additional Examples Tests corresponding to Numbers 1 to 5 inclusive in Table I were made using sepiolite, substituting the latter material for tale. The results are comparable to those shown in Table I for these examples. Preparation of the samples employing the method of adding the sepiolite to the phosphoric acid is preferred. The results were good in all cases but varied With the separate additives, and as would be expected with the varying conditions employed in the separate tests.

The tables above show the formulation and composition and in addition illustrate the characteristics of my improved polymerization catalyst, particularly with respect to structural or compression strength and hardness (resistance to abrasion) both of which are indexes of the wearing qualities and hardness. The structural or compressive strength tests represent the total thrust in pounds using the proving ring method on prepared representative specimens of fairly uniform size and shape (approximately /6" to cube) and represent the average of several comparative determinations on each type. The hardness data were made employing the Mohs mineral scale which is conventional in determining the relative hardness of minerals. The hardness and compression strength of a standard containing 80% phosphoric acid and 20% kiesclgnhr (with no additive present) made under similar conditions, i.e. heating the mixture up to 600 F. to 650 F. for 4 hours showed a hardness of about 1 on the same scale and compression strength of 10 to 15. Heating the standard to between 700 F. and 800 F. for an additional several hours increased these values (of a standard) for hardness to about 1+ and the compression strength to about 35.

While it may not be necessary to heat to temperatures as high as the foregoing, I have found it to be desirable where the phosphoric acid content is greater than about 79 and up to 80% and above. In these cases I obtain a very considerable improvement (much greater than that shown by the standard) by heating the product between 750 F. and 850 F. and higher. For example, in Example 5 the improvement in compression strength by heating to the higher temperatures was over 50- points and the hardness was also very considerably improved. Moreover, I have found in these cases that the optimum additive (talc, etc.) content is between 5% and 10%, based on the mineral mix and 1% to 2% on the total.

With regard to polymerization activity the conventional method for the polymerization of propylene under controlled and comparable experimental conditions may be employed. The catalysts shown in tables vary within several percent only from the standard (about 97% to 101.0%) depending on the percentage of the additive, being in the lower range with the maximum additive and minimum phosphoric acid content shown in the tables and highest with the minimum additive which produces the desired improvement in compression strength and hardness and maximum phosphoric acid content. These values are consistent with reported data on a standard polymerization catalyst containing about 80%. phosphoric acid and kieselguhr. The generally assigned activity of the latter is about 80. Additional phosphoric acid in the catalyst incorporated in the mixture may exceed the standard, although small differences may be negligible from a practical viewpoint considering the greatly increased value as a result of greatly increased hardness and compression strength and of the prolonged life of the catalysts produced according to my invention.

The general procedure for producing catalysts with activities higher than the standard is to increase the phosphoric acid contents by increasing both the H PO and P 0 The latter may be varied considerably as it readily dissolves in the 85% phosphoric acid on Warming. The heavy liquid resulting from increased P 0 permits a somewhat reduced proportion of kieselguhr or increased proportion of total phosphoric acid While at the same time maintaining proper workability of the mixture. For the 9 higher phosphoric acid contents the additive should be between about 5% and 10% of the mineral mixture (kieselguhr and talc) or between 1% and 2% of the total, and the heating temperature should be increased as shown above, i.e. corelated with the acid content.

It is, of course, necessary in these special cases to maintain a proper and fairly close balance in the relative amounts of the various components including the phosphoric acid, the phosphorous pentoxide, the talc, etc. and kieselguhr in order to obtain an initial mixture that is workable, i.e. may be readily extruded and at the same time does not flow or deform on heating, and which at the same time will produce the desired hardness and compression strength while maintaining the activity of the final product.

In carrying out these formulations the sequence of mixing is a factor and as I have previously observed, there are advantages when the additive is added direct to the mixture of phosphoric acid and P At the other end of the scale, I may when desired, increase the kieselguhr content of the catalyst or the additive or both and reduce the phosphoric acid content, e.g. from 70 to 75% (or more) to make a catalyst of lower activity but otherwise of very high compression strength and hardness. The lower range of this special type represents a type which might be used only in very special cases, but the upper range, e.g. from 75% to 78% H PO might find considerable use, e.g. in alkylation. However, the ranges between 78% and 82% H PO (with corrections for additive) are preferred as these would be most widely employed for normal operations of polymerizing olefin gases to produce high octane motor fuels.

It is also to be emphasized that while not the most desirable procedure, adjustments in proportions of the components may be made after the initial mixture is made to develop certain desired properties.

As also pointed out previously, the procedure of mixing the additives disclosed herein with the mixture of phosphoric acid and phosphorous pentoxide is a part of my invention particularly from the process viewpoint and is preferred for the reasons stated, over the procedure of mixing the talc etc. and kieselguhr first and with the phosphoric acid, or by mixing the kieselguhr and the phosphoric acid and then adding the tale etc. However, all of these methods may be used and under some conditions the latter alternatives may be desirable. The proportions of the additive are also a general factor in my invention although not to be construed as limiting. Correlation of temperature and time of drying and/ or baking with the phosphoric acid content of the mixture is also an important factor for best results in my process and catalyst product.

Moreover, it will be understood that there are many variations in initial concentrations of phosphoric acid, the percentages and amounts of phosphorous pentoxide, which may be incorporated therein; as well as the quality and proportions of kieselguhr and the additive required to give a mixture of the proper consistency to be extruded and to be heated without deformation or flowing of the material being heated, and at the same time to produce the requisite properties of activity, hardness and compressive strength. Also it must be understood that there are variations in composition of raw materials and for all of these factors as well as the temperatures and time periods for drying and/or baking, the necessary adjustments must be made.

It is to be further understood that some reaction occurs between the additives employed herein and the phosphoric acid, and therefore by the term additive as used in the claims, I include the additives (talc, etc.) as such and or their reaction products in terms of the amounts or percentages of additives used and referred to as such. In view of all of the above, I do not desire to be unduly 10 limited by these factors except as they are within the broad spirit and scope of my invention.

I claim:

1. A polymerization catalyst comprising a dried mixture of a phosphoric acid and an inorganic support, said support consisting essentially of a natural porous silica material selected from the group consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive selected from the group consisting of talc, sepiolite and pyrophyllite, the said phosphoric acid comprising about 70% to 85% of the said mixture, said support containing not less than about of the said porous silica material and less than about 20% and more than. 1% of said additive, said support being further characterized in that the said porous silica material together with said additive comprises not more than about 30% of the mixture.

2. A polymerization catalyst comprising a dried mixture of a phosphoric acid and an inorganic support, said support consisting essentially of a natural porous silica material selected from the group consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive selected from the group consisting of talc, sepiolite and pyrophyllite, the said phosphoric acid comprising about 75 to of the said mixture, said support containing in the range of about 85 to 97% of the said porous silica material and in the range of 3% to 15% of said additive, said support being further characterized in that the said porous silica material together with said additive comprises less than about 25% of the mixture.

3. A polymerization catalyst comprising a dried mixture of a phosphoric acid and a mineral support, said support consisting essentially of a material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive selected from the group consisting of talc, sepiolite and pyrophyllite, the said phosphoric acid comprising about 75% to 85% of the said mixture, said support containing not less than about 80% of the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and less than about 20% and more than 3% of said additive, said support being further characterized in that the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth together with said additive comprises not more than about 25% of the mixture.

4. A polymerization catalyst comprising a dried mixture of a phosphoric acid and a mineral support, said support consisting essentially of a material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive consisting essentially of talc, the said phosphoric acid comprising about 75 to 85% of the said mixture said support containing not less than about 80% of the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and less than about 20% and more than 3 of said additive, said support being further characterized in that the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth together with said additive comprises not more than about 25% of the mixture.

5. A polymerization catalyst comprising a dried mixture of a phosphoric acid and a mineral support, said support consisting of a material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive consisting essentially of a silicate of magnesium, said phosphoric acid comprising about 75% to 85 of the said mixture, said support containing not less than about 80% of the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and less than about 20% and more than about 3% of said additive, said support being further characterized in that the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth together with said additive comprises not more than about 25 of the mixture.

6. A polymerization catalyst comprising a dried mixture of a phosphoric acid and a mineral support, said support consisting of a material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and an additive consisting essentailly of pyrophyllite, said phosphoric acid comprising about 75% to 85% of the said mixture, said support containing not less than about 80% of the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth and less than about 20% and more than about 3% of said additive, said support being further characterized in that the said material selected from the class consisting of kieselguhr, infusorial earth and diatomaceous earth together with said additive comprises not more than about 25% of the mixture.

7. An improved polymerization catalyst comprising a dried mixture of a phosphoric acid and an inorganic support, said support consisting essentially of a porous natural silica material selected from the group consisting of kieselguhr, infusorial earth and diatom-aceous earth and an additive consisting essentially of pyrophyllite, said additive being present in an amount of about 3% to 20% 12 of the said inorganic support and less than about 10% of the total mixture.

8. An improved polymerization catalyst comprising a dried mixture of a phosphoric acid and an inorganic support, said support consisting essentially of a porous natural silica material selected from the group consisting of kieselguhr, infusorial earth and diatomaceous earth and of an additive selected from the group consisting of talc, sepiolite, and pyrophyllite with a phosphoric acid, the said additive being present in an amount of about 3% to 20% of the said inorganic support and less than about 10% 0f the total mixture, the said phosphoric acid comprising about 75 to about 85% of the total mixture and the remaining component of the said catalyst consisting essentially of said porous natural silica material.

Ipatieif Mar. 5, 1935 Mavity May 13, 1952 

1. A POLYMERIZATION CATALYST COMPRISING A DRIED MIXTURE OF A PHOSPHORIC ACID AND AN INORGANIC SUPPORT, SAID SUPPORT CONSISTING ESSENTIALLY OF A NATURAL POROUS SILICA MATERIAL SELECTED FROM THE GROUP CONSISTING OF KIESEGUHR, INFUSORIAL EARTH AND DIATOMACEOUS EARTH AND AN ADDITIVE SELECTED FROM THE GROUP CONSISTING OF TALC, SEPIOLITE AND PYROPHYLLITE, THE SAID PHOSPHORIC ACID COMPRISING ABOUT 70% TO 85% OF THE SAID MIXTURE, SAID SUPPORT CONTAINING NOT LESS THAN ABOUT 80% OF THE SAID POROUS SILICA MATERIAL AND LESS THAN ABOUT 20% AND MORE THAN 1% OF SAID ADDITIVE, SAID SUPPORT BEING FURTHER CHARACTERIZED IN THAT THE SAID POROUS SILICA MATERIAL TOGETHER WITH SAID ADDITIVE COMPRISES NOT MORE THAN ABOUT 30% OF THE MIXTURE. 